Having recently purchased 2 taps, I noticed that both from different manufacturers stated that their warranty was void if not fitted by a licensed plumber. I can't see anything in the ACL ( Australian Consumer Law Guarantee) that allows an exclusion like this? If the failure is not caused by the method of installation, can they deny the claim? What do you think? As an example, I fitted a mixer tap and the tap sprung a leak due to corrosion after 10 months. The retailer ( Bunnings) agreed to exchange but warned that the warranty should have been refused as I fitted the tap. This tap also failed in the same way after about 9 months but I chose not to try for a new one as it was a cheap tap and I had 20 month total.